In recent years, services, in which it is possible to share, exchange, or browse various messages using the Internet, have come into wide use. Since it is difficult to recognize individuals on a network, users are identified by displaying a user image such as an icon, an avatar, etc., corresponding to each of the users. A technique to determine the arrangement of user images based on relationships between users has been proposed because relationships between users are not recognizable using just a simple list (e.g., refer to Patent Document 1).